fix(workspace-forking): let an optional custom-block boolean return to its default

A two-segment switch has no transition back to "nothing selected", so once a user
picked True or False there was no way to stop overriding the target workflow's
declared default — a single click pinned the flag for every later sync.

An optional boolean now carries a third `Default` segment, trailing the two real
values because choosing one is the common action and reverting is the escape
hatch. A required boolean keeps two: the Sync gate demands a value, so unset is
not a state it can end in and offering it would present an unsubmittable choice.

Reported by Greptile on #6871.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: icecrasher321

apps/sim/ee/workspace-forking/components/fork-sync/custom-block-input-control.test.ts

@@ -0,0 +1,54 @@
+/**
+ * @vitest-environment node
+ */
+import { describe, expect, it } from 'vitest'
+import {
+  CUSTOM_BLOCK_BOOLEAN_FALSE,
+  CUSTOM_BLOCK_BOOLEAN_TRUE,
+  CUSTOM_BLOCK_BOOLEAN_UNSET,
+  customBlockBooleanOptions,
+  customBlockInputControl,
+} from '@/ee/workspace-forking/components/fork-sync/custom-block-input-control'
+
+describe('customBlockInputControl', () => {
+  it('matches how the canvas renders each field type', () => {
+    // Mirrors `subBlockTypeForField`: a field configured here must behave the way it will
+    // once the block is open in the editor.
+    expect(customBlockInputControl('boolean')).toBe('switch')
+    expect(customBlockInputControl('object')).toBe('textarea')
+    expect(customBlockInputControl('array')).toBe('textarea')
+    expect(customBlockInputControl('string')).toBe('input')
+    expect(customBlockInputControl('number')).toBe('input')
+  })
+
+  it('falls back to a plain input for an unknown or absent type', () => {
+    expect(customBlockInputControl('something-new')).toBe('input')
+    expect(customBlockInputControl(undefined)).toBe('input')
+  })
+})
+
+describe('customBlockBooleanOptions', () => {
+  it('lets an OPTIONAL flag return to the workflow default', () => {
+    // Without this a single click permanently pins the flag: a two-segment switch has no
+    // transition back to "nothing selected", so every later sync would keep overriding the
+    // child's declared default.
+    const options = customBlockBooleanOptions(false)
+
+    expect(options.map((o) => o.value)).toEqual([
+      CUSTOM_BLOCK_BOOLEAN_TRUE,
+      CUSTOM_BLOCK_BOOLEAN_FALSE,
+      CUSTOM_BLOCK_BOOLEAN_UNSET,
+    ])
+  })
+
+  it('offers a REQUIRED flag only real values', () => {
+    // The Sync gate demands a value, so "unset" is not a state it can end in — offering it
+    // would present a choice that cannot be submitted.
+    const options = customBlockBooleanOptions(true)
+
+    expect(options.map((o) => o.value)).toEqual([
+      CUSTOM_BLOCK_BOOLEAN_TRUE,
+      CUSTOM_BLOCK_BOOLEAN_FALSE,
+    ])
+  })
+})

apps/sim/ee/workspace-forking/components/fork-sync/custom-block-input-control.ts

@@ -31,8 +31,30 @@ export function customBlockInputControl(fieldType: string | undefined): CustomBl
 export const CUSTOM_BLOCK_BOOLEAN_TRUE = 'true'
 export const CUSTOM_BLOCK_BOOLEAN_FALSE = 'false'
 
-/** Segments for a boolean input, in the order a switch reads them. */
-export const CUSTOM_BLOCK_BOOLEAN_OPTIONS = [
+/**
+ * The unset value. Distinct from `false`: it means the sync writes no value at all, so the
+ * target workflow's Start field keeps whatever default it declares.
+ */
+export const CUSTOM_BLOCK_BOOLEAN_UNSET = ''
+
+const BOOLEAN_VALUE_OPTIONS = [
   { value: CUSTOM_BLOCK_BOOLEAN_TRUE, label: 'True' },
   { value: CUSTOM_BLOCK_BOOLEAN_FALSE, label: 'False' },
 ] as const
+
+const BOOLEAN_OPTIONAL_OPTIONS = [
+  ...BOOLEAN_VALUE_OPTIONS,
+  // Trails the two real values: choosing one is the common action, returning to the default
+  // is the escape hatch. Without it a single click would permanently pin an optional flag,
+  // since a two-segment switch has no transition back to "nothing selected".
+  { value: CUSTOM_BLOCK_BOOLEAN_UNSET, label: 'Default' },
+] as const
+
+/**
+ * Segments for a boolean input. An OPTIONAL field gets a third `Default` segment so the user
+ * can stop overriding the child workflow's declared default; a REQUIRED one does not, because
+ * the Sync gate demands a value and "unset" is not a state it can end in.
+ */
+export function customBlockBooleanOptions(required: boolean) {
+  return required ? BOOLEAN_VALUE_OPTIONS : BOOLEAN_OPTIONAL_OPTIONS
+}

apps/sim/ee/workspace-forking/components/fork-sync/fork-sync-view.tsx

@@ -34,7 +34,7 @@ import {
 } from '@/ee/workspace-forking/components/fork-sync/cleared-refs-list'
 import { forkRefKey } from '@/ee/workspace-forking/components/fork-sync/copy-reconciliation'
 import {
-  CUSTOM_BLOCK_BOOLEAN_OPTIONS,
+  customBlockBooleanOptions,
   customBlockInputControl,
 } from '@/ee/workspace-forking/components/fork-sync/custom-block-input-control'
 import { DependentFieldSelector } from '@/ee/workspace-forking/components/fork-sync/dependent-field-selector'
@@ -233,7 +233,7 @@ function DependentSelector({
         return (
           <ChipModalField {...shared} type='custom'>
             <ChipSwitch
-              options={CUSTOM_BLOCK_BOOLEAN_OPTIONS}
+              options={customBlockBooleanOptions(field.required)}
               // Passed through unmapped: an unset field is `''`, which matches neither
               // segment, so the switch renders with nothing selected. Coercing it to False
               // would show a required flag as configured while the Sync gate still reads it